This invention relates to a profile grinder for grinding the profile of rails of a railroad track. More specifically, it relates to a profile grinder useful for grinding welded joints connecting rails of a railroad track.
Railroad rails are welded in place using several methods. These welded joints require grinding in order to produce a uniform surface. This process is most commonly performed with hand operated grinders. Although various configurations are used, most of the grinders used for smoothing welded joints on rails are mounted on rollers with manual control of the pressure applied to the grinding stone or wheel. Inconsistency of the surface and nicks in the rail surface due to lack of control result in areas of stress concentration which can and have resulted in catastrophic failure of the rail. Therefore, there is a need for improved accuracy in grinding such weld joints.
Various rail grinder vehicles have been used for grinding out distortions and surface irregularities in the rails of a railroad track. Among those prior designs is the rail grinder of U.S. Pat. No. 4,779,384 of Shoenhair, assigned to the assignee of the present application, and hereby incorporated by reference. The rail grinder vehicle according to that patent has four grinders mounted on each side of the vehicle, each grinder including a grind motor, a grindstone, and a feed jack for moving the grindstone against and away from a rail. The rail grinder of that patent is especially well suited for grinding long stretches of rails to smooth out the effects of long periods of use of the rails. As the vehicle moves along the rails, the four grindstones on each side may be simultaneously grinding the rails on each side of the track.
Although the Shoenhair design has been quite useful, there still exists a need for a smaller grinder vehicle for grinding to correct out of face problems and/or special problems at crossings and switches in the rails. Further, the range of orientations for the grindstone in the Shoenhair design is relatively good for the primary intended purpose of the Shoenhair grinder, but the range of orientations for the grindstone in the Shoenhair design does not include certain orientations which may be useful for grinding at specialized locations. The orientation of the grindstone in Shoenhair may be such that its lower surface is horizontal or is tilted towards the field side of the rail or tilted down towards the gauge side of the rail.
Various turntables have been used in numerous types of rail maintenance vehicles. Such turntables are used for rotating the vehicle relative to the rails so that the forward direction of the vehicle is changed from its previous orientation. Generally, such turntables are located near the center of the vehicle and include a hydraulic actuator which pushes a base against the roadbed in between the two rails of the railroad track. The base pushes down until the vehicle has been lifted off the rails. The operator and/or others then rotate the vehicle itself relative to the vertical shaft including the hydraulic actuator which extends from the base to the main frame of the vehicle. After the vehicle has been rotated 180.degree. about the vertical axis corresponding to the turntable, the hydraulic actuator is retracted until the rail engagement wheels of the vehicle have reestablished contact with the rails of the railroad track.
Although such turntables have been generally quite useful, stability requirements make it advisable to place the turntable at or near the center of the vehicle or center of weight distribution of the vehicle. However, even when the hydraulic actuator is retracted such that the base is off the ground, it can limit one's ability to place certain rail maintenance mechanisms near the center of the vehicle.